IR 05000454/1994006
| ML20029E129 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 05/06/1994 |
| From: | Huber M, Jeffrey Jacobson, Pegg W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20029E127 | List: |
| References | |
| 50-454-94-06, 50-454-94-6, 50-455-94-06, 50-455-94-6, GL-89-10, NUDOCS 9405170025 | |
| Download: ML20029E129 (11) | |
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l U. S. NUCLEAR REGULATORY COMMISSION REGION 111
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Report Nos.- 50-454/94006(DRS); 50-455/94006(DRS)
Docket Nos. 50-454; 50-455 License Nos. NPF-37; I;PF-66 Licensee:
Commonwealth Edison Company
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Opus West III 1400 Opus P1 ace Downers Grove, IL 60515 Facility Name:
Byron Station, Units 1 and 2 Inspection At:
Byron Site, Byron, Illinois
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Inspection Conducted: March 28 through April 14, 1994 Inspectors:
\\rJ OL h e TA"<w [Ds Nh/T[
M. P. Huber
"db Date
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'A}ut h T%t 7847Y
"O W. D. Pegg Date NRC Consultant:
M. Holbrook, Idaho National' Engineering Laboratory
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Approved By:
Sv
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Ed JohnM.Jacobson,Chieff Date Materials and Processes Section Inspection Summarv Jnspection from March 28 throuah April 14. 1994 Geoort Nos. 50-454/94006(DRSit 50-455]9400610RS))
Areas Inspected:
Routine, announced safety inspection of the implementation of the licensee's response to Generic letter (GL) 89-10, " Safety-Related Motor-0perated Valve (MOV) Testing and Surveillance" (2515-109).
Results: This inspection focused on the licensee's program implemented to address GL 89-10.
No violations were identified.
The MOV program was implemented in accordance with the licensee's commitments. An additional
inspection will be necessary in order to close-out the GL 89-10 program review i
l at Byron Station. Two inspection followup items (Sections 2.2.2 and 2.3.1)
and one unresolved item were identified (Section 2.3.3).
i 9405170025 940509 i
PDR ADOCK 03000454 O
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. Inspection Summary.
The licensee demonstrated strengths in the GL 89-10 program implementation:
Conservative thrust values from differential pressure. (DP) testing were used to calculate dynamic valve f actors (Section 2.5).
Errors associated with diagnostic equipment accuracies were quantified as a result of testing performed by the licensee (Section 2.5).
The minimal effort associated with the butterfly valve testing program was considered a weakness (Section 2.8).
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TABLE OF CONTENTS Page
1.0 Persons Contacted....................................................
2~0 Inspection of the Implementation of the Program
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Developed in Response to Generic Letter 89-10......................
2.1 Program Scope...................................................
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2.2 Design Basis Reviews............................................
2.2.1 Differential Pressure and Flow Requirements..............
2.2.2 Degraded Voltage Calculations............................
2.3 Design Basis Capability.........................................
2.3.1 MOV Switch Settings......................................
q 2.3.2 Di f ferenti al Pre s sure Testi ng............................
2.3.3 Static Testing.................
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2.3.4 Differenti al Pressure Testing Scope......................
2.4 MOV Brakes......................................................
2.5 Evaluation of Test Data and VOTES Traces........................
2.6 Schedule........................................................
2.7 Periodic Verification of M0V Capability.........................
2.8 But terfly Valve Testing Program.................................
2.9 Pressure Locking and Tharmal Binding............................
3.0 L i c e n s e e S e l f-A s s e s s me n t.............................................
40 Inspection Followup Items............................................
5.0 Unresolved items.....................................................
6.0 Exit Meeting....................
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l QfTAILS 1.0 Persons Contacted Commonwealth Edison Company (CECO)
- K. Schwartz, Station Manager
- B. Adams, Regulatory Assurance, Nuclear Engineering and Technology Support
- B. Branson, MOV Support Engineer
- M. Browning, MOV Support Engineer
- E. Campbell, Support Services Director
- P. Dietz, Mechanical and Structural Engineering Programs Supervisor
- P. Enge, NRC Coordinator
- T. Gierich, Maintenance Superintendent
- P. Johnson, Technical Superintendent
- K. Passmore, Site Engineering and Construction Station Support &
Engineering Supervisor
- M. Ryterski, Site Engineering and Construction Station Support Electrical Lead
- N. Stremmel, MOV Coordinator
- S. Swanigan, MOV Support Engineer
- T. Tulon, Operations Manager
- B. Vivian, Construction Support
- W. Walter, Operations Engineer
.U. S. Nuclear Requlatory Commission
- H. Peterson, Senior Resident inspector
- Denotes those attending the management interview conducted on April 14, 1994.
Other persons were contacted during the course of the inspection.
2.0 1D1pection of the Imolementation of the Proaram Developed in Response to Generic Letter (GL) 89-10 This Phase 2 inspection verified and evaluated the licensee's GL 89-10 program implementation by examining a cross-section of the Byron motor-operated valve (MOV) population. The following MOVs were reviewed during this inspection.
ICC94138 Reactor Coolant Pump (RCP) Componen^. Cooling (CC) Supply Upstream Isolation ICC9414 RCP CC Return Outside Containment Isolation 2CC9415 Service Loop Isolation 2CC9438 RCP Thermal Barrier Isolation 2CV810S Charging Pump Discharge Header Containment Isolation IRH611 Residual Heat Removal (RHR)_ Pump B Miniflow Control 2RH8716A RHR Heat Exchanger -(HX) A Outlet Crosstie Isolation 2RH87168 RHR HX B Outlet Crosstie Isolation 2S18804B RHR HX B to Safety Injection (SI) Pump Suction
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Isolation j
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1SI8807A CV Pump Suction to S1 Pump Suction Crosstie Isolation IWOOO68 RCFC A/C Cooling Coils Inlet Containment Isolation 2.1 Proaram 52me The inspectors reviewed the safety-related MOV population and verified
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that the MOV program was consistent with GL 89-10 recommendations.
The program scope consisted of 257 MOVs of which 182 were rising stem valves and 75 were butterfly valves. Since the Part I inspection, the reactor coolant loop stop isolation valves, the loop stop bypass valves, and the positive displacement pump recirculation valves were removed from the GL 89-10 program. The justification for the removal of these valves was sa t i s factory.
2.2 Desian Basis Reviews 2,2.1 Differential Pressure and flow Reouirements The inspectors reviewed the design basis maximum expected differential pressure (DP) calculations and found them to be acceptable.
The piping diagrams, Final Safety Analysis Report, Technical Specifications, normal, abnormal and emergency operating procedures, and other plant documents were reviewed to determine the worst case design basis conditions for the sample of MOVs reviewed.
The conditions assumed were appropriate.
Certain mispositioning scenarios that resulted in DPs significantly higher than those calculated for design basis conditions were excluded.
The licensee identified and tracked each MOV in the GL 89-10 program that was configured assuming a DP less than the calculated mispositioning DP, consistent with their original GL 89-10 commitments.
Additional action may be warranted pending revised guidance from the NRC on the mispositioning issue for pressurized water reactors.
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2.2.2 Degraded Voltage Calculations The inspectors reviewed the methodology for performing degraded voltage calculations for AC MOVs and concluded that the methodology was acceptable.
No DC powered MOVs were used in safety-related applications at Byron.
Calculations assumed an appropriate grid voltage based on the second level under-voltage relay setpoint minus the relay tolerances.
Cable temperatures used in the calculations reflected the design basis ambient temperatures and the motor current was conservatively assumed to be the locked rotor current.
One concern was identified with the degraded voltage calculations.
Some of the calculations used a nonconservative power factor which was based
on generic motor curves that provided power factors at currents below those at the assumed locked rotor condition.
The locked-rotor power factor values published by the vendor were not utilized.
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The inspectors and the licensee staff recalculated the MOV terminal voltage using more conservative power factnrs and determined that the
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difference in motor terminal voltage was insignificant. Additionally, the licensee was conducting a motor test program and should be able to determine the appropriate motor performance characteristics to apply to M0V calculations. Although the safety significance of this was minimal, the inspectors consider the use of nonconservative power factors to be inappropriate and will reexamine the calculations after the licensee completes the motor test program and the results are incorporated into the MOV calculations.
This was considered an inspection follow-up item (50-454/94006-01(DRS)).
2.3 Dr,ian Basis capability 2.3.1 MJV Switch Settinas MOV capability to operate under design-basis conditions was evaluated by c lculating the available thrust using the standard thrust equation.
Mean seat diameter and various valve factors (determined from dynamic testing) were used.
The target thrust windows included margins for stem lubrication degradation and load sensitive behavior as appropriate.
Information from Limitorque Technical Update 93-03 regarding motor torque losses at elevated temperatures was incorporated into the target thrust calculations.
l For those valves that could not be dynamically tested, the licensee used a standard thrust equation to determine the thrust requirements.
Byron uses a variety of valve factor assumptions, based on best available data for a given valve type, that start at 0.40 for wedge gate valves and 1.10 for globe valves.
For the determination of actuator output thrust capability, Byron typically assumed a stem coefficient of 0.15.
A margin to account for stem lubricant degradation was included.
Further, a margin of 5% was set aside to address MOV load sensitive behavior (LSB) (also known as rate of loading), for those valves not setup with in-plant dynamic test data. Thrust requirements for setting of actuator torque switches were adjusted to account for diagnostic equipment inaccuracy and torque switch repeatability.
The licensee planned to je:tify assumptions (e.g., valve factor and load sensitive behavior) used in the sizing equation for non-DP testable
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valves by grouping the valves based on similar valve / actuator and system characteristics.
Performance of dynamically tested MOVs within the group will be evaluated and form the basis for values to be assigned to other members of that group. The data review was not complete at the time of the inspection. Review of the completed efforts in this area will performed during a future ir,spection.
When the capability of a MOV was questionable, conservatisms were reduced to increase the calculated capability for AC MOVs and establish operability.
White Paper MOV-WP 125, " Installed Motor Capability Evaluation," was used as an interim position to support testing and to establish a torque switch setting until a modification to enhance margin would be completed. The licensee indicated that the methodology described in the white paper could be used if problems with MOVs were to arise from future vendor notifications (such as a Part 21 issue), not to support long-term operations. Testing was not complete to support this position; however, no MOVs at Byron had their torque switches set based
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using the MOV-WP 125 methodology.
Since the operability methodology may
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overestimate the capability of the MOVs, this position was considered an inspection followup item pending the completion of the licensee's test program and further review by the NRC (50-454/94006-02(DRS)).
2.3.2 Differential Pressure Testina The inspectors reviewed test results, dynamic test packages, and post-test review packages for the selected valves.
This review indicated closing gate valve factors up to 1.6 and LSB as high as 54.7%.
Stem friction coefficients for the sample valves were as high as 0.27 under dynamic conditions (see Attachment 1)'.
Parallel train valve operability was addressed where applicable.
Some problems were identified with DP.
testing procedures and test acceptance criteria; however, no operability concerns were identified.
Some corrections to the procedures and acceptance criteria were implemented prior to the inspection. Work in these areas was continuing and will be further evaluated during a future inspection.
Dynamic test acceptance criteria contained in procedure IBHS XLT-2,
"Limitorque Valve Operator Diagnostic Test," did not include a requirement for extrapolation and assessing design-basis thrust margin in the close direction prior to returning the MOV to service for those cases where the dynamic test conditions were less than design-basis conditions. To address problems with previous test acceptance criteria identified during inspections of other Ceco plants, the licensee initiated a margin assessment of all dynamic tests prior to the inspection, reviewing the tests using appropriate acceptance criteria and updated vendor information. No operability concerns were identified during this review. The licensee developed a methodology, described in white paper MOV-WP 126, " Text Closecut Criteria for DP Testing," for performing future DP test reviews prior to return to service. Although the methodology appeared to address the concerns about extrapolating the DP to design-basis conditions in the close direction, the procedure did not address extrapolating the highest opening force due to differential pressure effects (V0TES mark 010) to design-basis conditions for wedge gate valves.
The licensee based this on an assumption that the highest forces for wedge gate valves would always occur at disc pullout (VOTES mark 09).
The inspectors indicated that some industry testing showed that forces necessary to overcome DP effects may exceed the forces required at disc pullout.
The licensee agreed to evaluate this issue to determine the best way to incorporate a comparison of the extrapolated forces at 010 to the force present at 09 into test procedures.
The-licensee will be expected to justify its method of extrapolation to complete their GL 89-10 program. A review of the revised method for evaluating design-basis capability will be conducted during a future inspection.
The problems with the DP testing procedures were the result of faulty
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logic for measuring differential pressures during testing.
SPP 92-70,
" Differential Pressure Test of ICC94138," incorrectly identified the
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closing differential pressure as 23 psid, when it was later determined during a post-test evaluation to be 138 psid.
The logic for calculating the DP was incorrect and was the cause of the error.
The inspectors were concerned that poor test procedures could provide incorrect-valve
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performance characteristics.
The licensee will evaluate future dynamic test procedures to ensure that the procedure logic was correct.
The inspectors will review these efforts during a future inspection.
2.3.3 Static Testino During review of the static test packages, the inspectors identified instances where the most current thrust window, which is provided by corporate engineering, was not used when setting up MOVs statically.
For example, a thrust window of 3700 lbf to 5230 lbf was used for static setup of ICC9414; however, the rising stem M0V data sheet (RSMDS) was revised and approved on the day of the static test and included a more conservative minimum required thrust of 4300 lbf.
In another case, the RSMDS for IS18807A specified a window of 7590 to 10000 lbf; however, the test procedure used a window of 5341 lbf to 12500 lbf.
In both cases, the as-left thrust at control switch trip (CST) was within the bounds of both the old and new thrust windows, but the inspectors were concerned with the lack of coordination between corporate engineering and the site-regarding the scheduling of MOV testing activities and the control of MOV thrust windows.
Licensee personnel stated that the paperwork process induced a time lag that prevented use of the new calculations, but were in the process of implementing procedural changes to ensure that the site used the most current thrust windows.
The inspectors will review the licensee's efforts during a future inspection.
As a result of corrections to previous test data, the licensee found several valves that exceeded the manufacturer's torque rating for the actuator by as much as 150%.
The overtorque conditions were evaluated and accepted for interim operation based on the position established by corporate engineering in White Paper MOV-WP 122, "Limitorque Operator Thrust and Torque Rating Extension." This method was.used to determine the allowable cycles remaining before an MOV might be damaged.
Plans were in place to reset the torque switches and inspect the MOVs for wear and damage during upcoming refueling outages.
The acceptability of this approach was not established at the time of the inspection and communications were ongoing between NRC and Ceco.
Acceptability of this position may affect the current status of M0Vs.
This was considered an unresolved item pending the outcome of ongoing discussions between NRC and CECO (50-454/94006-03(DRS)).
2.3.4 Differential Pressure Testino Scope i
The licensee planned to DP test 100 rising stem MOVs, the total number
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prac ticabl e.
The number of DP tests planned for butterfly MOVs was not yet available. The inspectors also reviewed the justification for excluding certain GL 89-10 MOVs from DP testing and did not identify any u
MOVs that were improperly excluded.
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2.4 MOV Brakes Motor brakes were not utilized on any M0V in the Byron GL 89-10 program and therefore were not a concern.
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P 2.5
[ valuation of Test Data and VOIES Traces DP traces were evaluated to determine the valve factor under dynamic conditions. The licensee used the highest thrust measured before hardseat contact to calculate the dynamic valve factor, a method to determine conservative valve factors. Additionally, test data was gathered to support open stroke calibration range extrapolation testing being performed by Liberty Technology. The data was used to provide accuracy numbers for extrapolating test data in the stem tension region, which is usually not included when performing the calibration of the equipment during initial valve testing.
These efforts by the licensee were considered strengths.
2.6 Schedq]e of the 257 MOVs in the GL 89-10 program. 182 were rising stem gate and globe valves.
Static testing was complete on 162. Dynamic tests were scheduled for 100 rising stem valves with 87 completed.
The testing program plans for the 75 butterfly M0Vs was not yet implemented at the time of the inspection.
The remaining 20 static and 13 dynamic were scheduled for completion within the current commitment date (by the enn of the Unit outages scheduled for fall of 1994 and spring IPS for Units 1 and 2, respectively).
The licensee also stated their intent to complete the butterfly testing program within the schedule committed to in response to GL 89-10.
2.7 Periodic Verifica_ tion of 110V Capability The licensee planned to use static diagnostic testing to periodically verify MOV capability; however, static testing may not be adequate to model MOV behavior under dynamic conditions.
The frequency of the periodic verification was inconsistent with the GL 89-10 guidance with the exception of high safety significant MOVs. Justification for both the method and the frequency of testing used to provide assurance of MOV operability will be reviewed during a future inspection.
2.8 Butterfly Valve Testina Pro 1r_am a
The butterfly MOV testing program did not progress at the same pace as the rising stem testing program.
Preliminary plans.were discussed and it appeared that the testing program would begin around July 1994.
The plan for closure of GL 89-10 activities on the butterfly valve population will be docketed when complete. Although plans for butterfly valve testing were being developed and preliminarily scheduled for completion on schedule, the delay in the implementation of the butterfly testing program was considered a weakness.
2.9 Pressure LoSkina and Thermal Bindina The potential for pressure locking and thermal binding was being reexamined in response to recent industry experience and regulatory guidance.
The licensee staff had reviewed these issues previously and determined that they were not applicable to Byron Station.
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Although progress to resolve these issues was. limited to date, the licensee staff performed an initial screening of all valves in the GL 89-10 program and an action plan was in place to screen, rank, and develop a schedule for closure of each valve in the program.
The inspectors reviewed the initial screening and determined that the 1(2)Ril8716A/B heat exchanger outlet crosstie isolation valves had not been identified as being susceptible tr, pressure locking.
NUREG-1275, Volume 9. " Operating Experience feedback Report - Pressure Locking and Thermal Binding of Gate Valves," identified these MOVs as susceptible to pressure locking. The licensee staff intended to perform a more rigorous final' review within a few months and committed to examine the susceptibility of the 1(2)Ril8716A/B valves to pressure locking more i
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closely during that review. Actions regarding pressure locking and thermal binding will be reviewed and evaluated in a future inspection.
3.0 Licensee Self-Assessment The licensee had conducted self-assessments of their MOV program.
Various issues were identified and were being addressed.
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informal methods were used to perform a self-critical look at the MOV program and program implementation. No engineering program reviews were conducted by the quality verification organization, but a program review
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was a candidate for a future audit.
This area appeared to be acceptable.
4.0 Inspection Followun Items Inspection followup items were matters which have been discussed with the licensee, which will be reviewed further by the inspectors, and which involve some action on the part of the NRC or licensee or both.
Inspection followup items disclosed during this inspection were discussed in Sections 2.2.2 and 2.3.1.
5.0 Unresolved 11 ems Unresolved items are matters about which more information was required In order to ascertain whether they are acceptable items, items of noncompliance, or deviations. An unresolved item disclosed during this inspection is discussed in Section 2.3.3 of this report.
6.0 Exit Meeting The inspectors met with licensee representatives (denoted in Paragraph 1) at the conclusion of the inspection on April 14, 1994.
The inspectors summarized the purpose and scope of the inspection and the findings.
The inspectors also discussed the likely informational content of the inspection report with regard to documents or processes reviewed during the inspection. The licensee did not identify any such documents or processes as proprietary.
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ATTACHMENT 1 BYRON VALVE DATA val.VE VALVE SilE TEST PERC[NI STEM DYNAMIC LOAD NLMBER AND CONDITIONS DESIGN TRICTION VALVE 5tN5filVE MANUfACTlRER (psid)
BASIS C0f f flCIE NT FACIOR'
BDtAVIOR'
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OPI N CLOSE OPEN CLOSE DINANIC STAllC ICC94138 6" VELAN 136 138
99 0.13'
O.14'
O.49-4.3 150' GATE VALVE ICC9414 6" VELAN 127 127
91 0.13'
O.15'
O.73-6.7 150' GAIE VALVE 1RH611 3" VESTINGHOUSE 154 154
78 Unk nown 0.12 1.68-0.2 1840' GATE VALVf 1518807A 6" VEST!NCHOUSE 180 180
75 0.27 0.11 0.33 54.7 150' GATE VALVE IWOOO68 10" ANCHOR
16
93 0.22 0.24 0.39-10.0 DARLING 150' GATE val VE
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2CC9415 16" VELAN 127 127
91 0.17 0.23 0.49-26.7 150' GATE VALVE 2CE9438 4" VEL AN 116 110
83 0.20 0.21 0.27 6.6 300' ( ATE VALVE 2CV8105 3" WESilNGHOUSE 2574 2574
95 Unknown 0.12'
O.58 1.9 1500' GATE VALVE 2RH8716A 8" WESTINGHOUSE 175 175
83 Unknown 0.17'
O.01 0.0 300* GATE VALVE
?RH87168 8" WESTINGHOUSE 174 174
83 Unknown 0.14'
l.1-2.7 300* GATE val Vf 251M048 8" WESTINGHOUSE 172 172
70 0.17 0.11 0.08 0.0 300' GATE VALVE
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The dynamic valve factors listed were calculated by the licensee using a mean seat diameter.
- Stem Lubricant Nebula EP-1
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A negative number indicated that the thrust observed at CST during the dynamic test was greater than the thrust observed at CST during the static test.
Stem Lubricant Neolube unless indicated by *
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